The present invention relates to an automatic pallet changer for loading and unloading a pallet supporting a workpiece for a machine tool.
The known pallet changers of this kind are provided with an exchanger arm located between the table of the machine and the pallet receiver where the pallets are exchanged. The exchanger arm is rotatable around a vertical supporting shaft and also movable up and down along the shaft.
A disadvantage of this type of pallet changers is that the pallet exchange takes a relatively long time. The slow speed of pallet exchange is due to the fact that the exchanger arms must be long enough to reach and catch the peripheral portion of the pallet. As a result the radius of the circular movement of the exchanger arms becomes large, and they are in danger of colliding with other objects such as rails and guides which are used to transport the pallet to a place where the pallets are exchanged. In addition, because of the larger circular movement, the speed of the exchanger arms is unavoidably reduced.